The present invention relates generally to medical devices and procedures, and in particular aspects, to vascular guidewires and combinations thereof with other vascular devices, such as catheters, that can be beneficially used in animal and human patients when conducting procedures that employ intravascular ultrasound (IVUS) for imaging.
Guidewires useful for intravascular procedures can be constructed using various materials and techniques. For example, guidewires can be constructed of segments of metallic wire formed into coils or strands, or both. Wire guides may also be coated with one or more of a wide range of coatings, such as for example, Polytetrafluoroethylene (PTFE) for reduced friction, or an anticoagulation agent like Heparin to reduce blood clotting.
However, metal wire guides are highly reflective to ultrasound because the characteristic acoustic impedance of metallic substances causes substantially all of the sound waves to reflect off the device rather than passing through. Therefore, when metal guidewires are inserted into a patient and imaged using ultrasound imaging devices, various artifacts are routinely observed which can obscure important imaging features. For example, when a metallic guidewire is in use, a bright dot may be observed with a large shadow behind the wire.
These artifacts may be especially severe in IVUS imaging. Due to space, size, and cost (i.e. one time use) limitations, IVUS transducers may have lower overall performance as compared to conventional transcutaneous transducers. Therefore, artifacts may be more pronounced further degrading image quality. The artifacts may be especially severe if the wire is close to the IVUS transducer further reducing opportunities to obtain usable, and perhaps critically important, clinical information from the ultrasound image.